Piao Zhengyu, Park Jin Kyung, Patel Madhumita, Lee Hyun Jung, Jeong Byeongmoon
Department of Chemistry and Nanoscience, Ewha Womans University, 52 Ewhayeodae-gil, Seodaemun-gu, Seoul, 03760, Korea.
ACS Macro Lett. 2021 Nov 16;10(11):1436-1442. doi: 10.1021/acsmacrolett.1c00584. Epub 2021 Nov 4.
The control of ice recrystallization is very important in cryo-technological fields such as the food industry, biopharmaceuticals, and cell storage. Ice recrystallization inhibition (IRI) compounds are therefore designed to limit the growth of ice crystals, decrease the crystal size, and control the crystal shape. To improve the IRI activity of cryo-systems, various synthetic polymers such as biomimetic polypeptides from polar fish, facially amphiphilic polymers, polyampholytes, poly(vinyl alcohol) derivatives, and block copolymers with hydrophilic-hydrophobic balance have been developed. Except for graphene oxide, poly(vinyl alcohol) has thus far exhibited the best performance among these polymers. Herein, poly(l-alanine--l-lysine) (PAK) was shown to exhibit a similar IRI activity to that of poly(vinyl alcohol). Moreover, in contrast to the needle-shaped ice crystals generated by the aqueous PVA solution, the PAK solution was shown to generate cubic-to-spherical shaped ice crystals. Furthermore, neither poly(l-alanine--l-aspartic acid) (PAD) nor poly(ethylene glycol) (PEG) with a similar molecular weight provided any significant IRI activity. Examination by FTIR and circular dichroism spectroscopies indicated that the PAK forms α-helices, whereas the PAD forms random coils in water. Further, a dynamic ice shaping study suggested that PAK strongly interacts with ice crystals, whereas PAD and PEG only weakly interact. These results suggest that PAK is an important compound with superior IRI activity and that this activity is dependent upon the functional groups and secondary structure of the polypeptides.
在食品工业、生物制药和细胞储存等低温技术领域，控制冰的重结晶非常重要。因此，冰重结晶抑制（IRI）化合物旨在限制冰晶的生长、减小晶体尺寸并控制晶体形状。为了提高低温系统的IRI活性，人们开发了各种合成聚合物，如来自极地鱼类的仿生多肽、表面两亲聚合物、聚两性电解质、聚乙烯醇衍生物以及具有亲水-疏水平衡的嵌段共聚物。到目前为止，除了氧化石墨烯外，聚乙烯醇在这些聚合物中表现出了最佳性能。在此，聚（L-丙氨酸-L-赖氨酸）（PAK）被证明具有与聚乙烯醇相似的IRI活性。此外，与PVA水溶液产生的针状冰晶不同，PAK溶液产生的是立方到球形的冰晶。此外，具有相似分子量的聚（L-丙氨酸-L-天冬氨酸）（PAD）和聚乙二醇（PEG）均未表现出任何显著的IRI活性。傅里叶变换红外光谱（FTIR）和圆二色光谱研究表明，PAK在水中形成α-螺旋，而PAD形成无规卷曲。此外，动态冰成型研究表明，PAK与冰晶强烈相互作用，而PAD和PEG与冰晶的相互作用较弱。这些结果表明，PAK是一种具有优异IRI活性的重要化合物，且这种活性取决于多肽的官能团和二级结构。
